Vitamin D is a group of vitamins, with D3, cholecalciferol/calcifediol/calcitriol, and D2, ergocalciferol, being the most important.

Health considerations

Vitamin D is essential to bone health, normal immune system function, normal inflammatory response and muscle function, and avoidance of rickets and osteomalacia, or softening of bones. Excessive vitamin D intake (following supplementation) can cause hypercalcemia, leading to a variety of severe negative health effects. There is some evidence for optimal vitamin D levels being protective against the development of colon cancer, and suggestions from research of it being important in the prevention of diabetes, high blood pressure, and other diseases.   Excessive vitamin D levels may increase the risk of a variety of negative health effects, including pancreatic cancer and cardiovascular events.

Keep in mind

Dairy products are typically fortified with vitamin D. Those with milk allergies should be aware of alternative sources. Some medications can interfere with vitamin D absorption.

May be found in

Milk, milk products, non-dairy milk, mushrooms, eggs, fatty fish, fortified foods



Vitamins and Hormones

The Merck Manual

National Institutes of Health Office of Dietary Supplements

Alternative Spellings and Names

Vit D, cholecalciferol, ergocalciferol

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